I have noticed for some time now that the Red Bulls, the McLarens and Ferraris are really good at securing the driver in the car, where the lower teams are not so good. When you look at the in car shots of the Sauber or HRTs and the like, in many cases their legs particularly their left leg flops about rather loosely. Having done some driving I can tell you driver confidence in the car is paramount.Sometimes you can get more time from driver confidence than from suspension performance.
I can also say that not feeling well secured in the seat affects that confidence.
I have been wondering if those drivers couldn't gain a tenth or so if their legs weren't flying around in the cockpit.